There have been relatively few innovations in the methods of transporting and handling mortar and mortar/sand mixtures (i.e., dry mix) from the mortar preparation site to the construction site in the last decade. Introduction of the concept of premixing mortar/sand mixtures and packaging such mixtures in large quantities in weatherproof storage bags having lifting handles, has revolutionized the manner in which mortar is mixed and prepared at the construction site. A complete discussion of such process is found in my prior U.S. Pat. No. 4,956,821, the contents of which are herein incorporated by reference. The ability to premix and practically handle large quantities of mortar has greatly facilitated batch mixing operations at the construction site. As described in my prior patent, the premixed mortar is transported in large bulk bags of typically 2,000 to 3,000 pound quantities, to the construction site, where the bulk bags are unloaded into waterproof medium sized storage silos having a discharge outlet that can be selectively opened and closed to charge a batch mixer, for mixing batches of mortar, grout, or cement, as needed. In the past, it has been convenient for such medium sized silos to hold from five to seven bags of such premixed mortar at a time.
Such systems represent a vast improvement in the art and have significantly changed the dynamics of mortar preparation and handling at the construction site. In construction projects which extend over relatively long periods of time, it is practical to transport such medium sized storage silos to the construction site and to use them as described above. However, for the smaller construction projects that may require mixing of only one or two bulk bags of mortar at any one location, it may be inconvenient to transport and set up such medium sized silos for handling just several bulk bags of mortar. However, even for such smaller projects it is still desirable to use dry mortar which has been premixed and which is transportable to the site using the large bag technique.
There are other instances, even in larger construction projects wherein it may be more convenient to move the batch mixer and its supply silo between different locations at the construction site, rather than to continuously transport small batches of mixed cement from the mixer to where it is ultimately needed. However, in such cases it may be inconvenient to repetitively move a loaded storage silo around the construction site, to accommodate this need--particularly if it is substantially filled with five to seven tons of material. It would be desirable in such instances for a single bulk storage bag at a time to be elevated above a mixer and to selectively empty the bag into the mixer, for preparing a plurality of batches, until the bag is empty. However, the bulk bag technology has not heretofore accommodated such need.
To continuously elevate a mortar bulk storage bag over a batch mixer generally requires a forklift vehicle or a crane to continuously hold the bag in position. Such equipment is too expensive to inefficiently utilize in such disabling manner for any extended period of time. An alternative would be to use the lift equipment to raise the bag over the mixer to drop a batch from the bag whenever desired, and then to place the bag back into a protective storage area when not being used. However, to go through such labor intensive operations totally negates the purpose and efficiencies for which the bulk bag transport and handling concept was designed. Further, such large storage/transport bags are typically not designed for "selective" emptying since they do not have any controllable metering apparatus at their discharge ports. They usually are designed for emptying of the entire bag contents at a time and do not readily lend themselves to accurate interruption or stopping of a discharge process, with any degree of controllability, once the discharge process has been initiated. Their outlet port closure structure generally consists of a draw cord member fastened around a flexible tubular outlet chute, that once loosened, allows free discharge flow of the mortar through the chute until the entire contents of the bag passes therethrough.
Therefore, while the needs to adopt and to incorporate the advantages of the bulk transport/storage bag concepts to the smaller construction project exist, no practical approach which maintains the economies for which the system was designed has been devised in the art. The present invention provides a dispensing system that addresses these deficiencies and needs of the prior art.